Rosemount 3152 - Demodulator Function

Reference Manual
00809-0100-4835 Rev BD
July 2016
Rosemount 3150 Series
4-4
DEMODULATOR
The demodulator consists of a diode bridge that rectifies the ac signal
from the sensor cell to a dc signal. The oscillator driving current, I
ref
(the
sum of the dc currents through two transformer windings), is kept a
constant by an integrated circuit operat
ional amplifier (op amp). The
output of the demodulator is a current directly proportional to pressure,
i.e.
,
( )
1
2
CCfV
I
pp
diff
−=
−
The diode bridge and temperature compensation circuits are located
inside the sensor module.
Capacitor Plates
Silicon Oil
Isolating Diaphragms
Center Diaphragm
Rigid
Insulation